Physicsless part

Delta-V comparison of three RV-105 RCS Thruster Block as massless and normal parts, before the changes introduced in 1.0.1

Physicsless parts are parts where the physics don't work in the usual way. The mass of the part and the drag experienced by it are added to the parent's part. The part itself has no mass nor drag at its point of placement, but it still contributes to the vehicle's total mass and drag; in short, during movement, the added physicless parts would not generate mass-shift and drag that affects lateral stability. Before 1.0.1 the mass and the drag weren't added to the parent but just ignored. It is influenced by the PhysicsSignificance flag in the part configuration which must be set to 1 to make it physicsless.

When constructing a craft, the root part can't be such a part.

Behaviour

A craft with only physicsless parts starts to oscillate after a short time and then starts to destroy itself. But this is usually not possible because the root part is always not a physicsless part. The game can change the property on the fly, so that when a new root part after decoupling would be physicsless the game removes that special status.

List of physicsless parts

Physicsless parts as of 1.10.1:

• 2HOT Thermometer
• Atmospheric Fluid Spectro-Variometer
• BZ-52 Radial Attachment Point
• Communotron 16-S
• Communotron 16
• Communotron 88-88
• Cubic Octagonal Strut
• Double-C Seismic Accelerometer
• EAS-4 Strut Connector
• FL-A5 Adapter
• FTX-2 External Fuel Duct
• GRAVMAX Negative Gravioli Detector
• Illuminator Mk1
• Illuminator Mk2
• Kelus Mobility Enhancer
• Kelus-LV Bay Mobility Enhancer
• O-10 "Puff" MonoPropellant Fuel Engine
• Octagonal Strut
• OX-STAT Photovoltaic Panels
• Pegasus I Mobility Enhancer
• Place-Anywhere 7 Linear RCS Port
• PresMat Barometer
• RFP-0 Flag (0.625 m)
• RFP-1 Flag (1.25 m)
• RFP-2 Flag (2.5 m)
• RFP-3 Flag (3.75 m)
• RFP-F Flag Flat
• RV-105 RCS Thruster Block
• Vernor Engine
• Z-100 Rechargeable Battery Pack
• Z-400 Rechargeable Battery

Note that several parts, such as the LT-2 Landing Strut, have PhysicsSignificance = 0 in its part.cfg. This does nothing, and the part behaves as normal.

See also

• “Kerbal Space Program - Your Physics Have No Power Over Me!” by Scott Manley